Sorry, Treppenlaeufer, for your experience at check-in. You ask whether your expectations might be grounded in over entitlement. Difficult to say. I have had positive experiences when I stayed there last December. But we did not turn up that early
.
On the other hand, they could have checked with the EL host before outright declining your access to the EL. Space problem would count here. But your entitlement of breakfast only in the morning appears a bit cheap to me - for a Diamond.